Field of the Invention
The present invention relates to a technique enabling a transmission apparatus to transmit contents to a reception apparatus via a network. More particularly, the present invention relates to a technique for transmitting metadata indicating segment data receivable by the reception apparatus, which is a plurality of segment data constituting a content, from the transmission apparatus to the reception apparatus.
Description of the Related Art
As a technique for transmitting moving image data, Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2012-514276 discusses a transmission apparatus that stores moving image data to be transmitted in a plurality of segment data, and transmits each segment data to a reception apparatus via a network.
The transmission apparatus discussed in Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2012-514276 associates address information needed by the reception apparatus to receive the segment data with each segment data. As the address information, for example, a uniform resource identifier (URI) is associated with each data.
The transmission apparatus transmits to the reception apparatus, in response to a request from the reception apparatus, metadata (hereinafter, referred to as playlist) including a plurality of pieces of address information associated with the plurality of segment data.
The reception apparatus discussed in Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2012-514276 requests the segment data based on the address information included in the received playlist, and receives the segment data from the transmission apparatus.
The transmission apparatus discussed in Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2012-514276 updates the playlist after new data has been added to the moving image data to be transmitted. When a new playlist request arrives from the reception apparatus after the playlist has been updated, the transmission apparatus discussed in Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2012-514276 transmits the updated playlist to the reception apparatus.
It is discussed in Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2012-514276 that when the transmission apparatus updates the playlist, the URIs of the segment data can be eliminated from the playlist in the order of addition to the playlist.
Japanese Patent Application Laid-Open No. 2007-74684 discusses a public server that sequentially receives segment data acquired by dividing moving image data from a video server, and generates a playlist each time a viewing request is received from a reception apparatus. The public server transmits the generated playlist to the reception apparatus.
The public server, which has received the viewing request from the reception apparatus, transmits a playlist of segment data after latest segment data reception of which by the public server from the video server had been completed at the time of receiving the viewing request to the reception apparatus. The number of pieces of address information of the segment data described in one playlist is set beforehand in the public server or designated from the reception apparatus.
Conventionally, no consideration has been given to a transmission situation of the segment data to the reception apparatus when the playlist is generated.
In a moving image delivery system discussed in Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2012-514276, a redundant playlist including the URI of the segment data already received by the reception apparatus may be transmitted to the reception apparatus.
In a moving image delivery system discussed in Japanese Patent Application Laid-Open No. 2007-74684, the reception apparatus receives the playlist of the latest segment data generated at the time of receiving the viewing request by the transmission apparatus and subsequent segment data. Thus, the reception apparatus cannot receive a playlist of the segment data before the latest segment data and not received from the transmission apparatus.